See https://gitlab.com/gitlab-org/gitlab-ce/issues/45608#note_113803790
for query and plan.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/45608.

Add an index to the `file_store` column on `lfs_objects`. This makes
counting local objects faster.

Also, there is no longer need to check for objects with `file_store`
being `NULL`. See
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/18557

---

### Query plans

#### Before & with `NULL`

```
Aggregate  (cost=113495.96..113495.97 rows=1 width=8) (actual time=1691.394..1691.394 rows=1 loops=1)
  ->  Seq Scan on lfs_objects  (cost=0.00..106415.50 rows=2832186 width=0) (actual time=0.012..1312.488 rows=2852607 loops=1)
        Filter: ((file_store = 1) OR (file_store IS NULL))
        Rows Removed by Filter: 131
Planning time: 0.077 ms
Execution time: 1691.433 ms
```

#### Before, without `NULL`

```
Aggregate  (cost=113495.96..113495.97 rows=1 width=8) (actual time=856.423..856.424 rows=1 loops=1)
  ->  Seq Scan on lfs_objects  (cost=0.00..106415.50 rows=2832186 width=0) (actual time=0.012..672.181 rows=2852607 loops=1)
        Filter: (file_store = 1)
        Rows Removed by Filter: 131
Planning time: 0.128 ms
Execution time: 856.470 ms
```

#### After & with `NULL`

```
Aggregate  (cost=68819.95..68819.96 rows=1 width=8) (actual time=583.355..583.355 rows=1 loops=1)
  ->  Index Only Scan using index_lfs_objects_on_file_store on lfs_objects  (cost=0.43..61688.35 rows=2852643 width=0) (actual time=0.028..399.177 rows=2852607 loops=1)
        Filter: ((file_store = 1) OR (file_store IS NULL))
        Rows Removed by Filter: 131
        Heap Fetches: 867
Planning time: 0.096 ms
Execution time: 583.404 ms
```

#### After, without `NULL`

```
Aggregate  (cost=68817.29..68817.30 rows=1 width=8) (actual time=490.550..490.551 rows=1 loops=1)
  ->  Index Only Scan using index_lfs_objects_on_file_store on lfs_objects  (cost=0.43..61685.68 rows=2852643 width=0) (actual time=0.040..311.760 rows=2852607 loops=1)
        Index Cond: (file_store = 1)
        Heap Fetches: 831
Planning time: 0.294 ms
Execution time: 490.590 ms
```

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/6067

Even though we currently only should have one group for a cluster, we
allow the flexibility to associate to other groups in the future.

This also matches the runner <=> groups association.

- Adds Cluster#first_group, aliased to Cluster#group. For the
conceivable future, a cluster will have at most one group.

- Prevent mixing of group and project clusters. If project type
clusters, it should only have projects assigned.  Similarly with groups.

- Default cluster_type to :project_type. As it's very small table we can
set default and null: false in one release.

It's possible that user pastes accidentally also unsubscribe link
which is included in footer of notification emails. This unsubscribe
link contains personal token which attacker then use to act as the
original user (e.g. for sending comments under his/her identity).

This model will be used to persist into database Kubernetes properties,
such as namespace, service account name and service account token.

This integration no longer works and does not appear to be supported.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/39697

Was introduced in the time that GitLab still used NFS, which is not
required anymore in most cases. By removing this, the API it calls will
return empty responses. This interface has to be removed in the next
major release, expected to be 12.0.

This makes a temporary implementation of the
Web IDE commits counter using Redis while
https://gitlab.com/gitlab-org/gitlab-ce/issues/52096
is being discussed further for a more generic
approach to counters

commit 9d9594ba20097dc4598f7eb42a9f9d78d73eae54
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Thu Sep 13 20:18:31 2018 +0900

    Cancel scheduled jobs

commit f31c7172e07a9eb03b58c1e62eaa18cda4064aa6
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Thu Sep 13 11:18:42 2018 +0900

    Add Ci::BuildSchedule

commit fb6b3ca638f40f9e1ee38b1fdd892bda4f6fede7
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Wed Sep 12 20:02:50 2018 +0900

    Scheduled jobs

Implements UsageCounters model to track feature usage counters
and makes easy to extend for future counters

- Creates a new column to hold the single patch limit value on
application_settings
- Allows updating this value through the application_settings API
- Calculates single diff patch collapsing limit based on
diff_max_patch_bytes column
- Updates diff limit documentation
- Adds documentation (with warning) as of how one can update this limit

We started syncing all the wiki regardless of the fact it's disabled or
not. We couldn't do that in one stage because of needing of smoth update
and deprecating things. This is the second stage that finally removes
unused columns in the geo_node_status table.

We remove this feature as it never worked properly

Explicitly persist the legacy_abac value of the cluster_provider_gcp so that we can disable abac if the `:rbac_clusters` feature flag is enabled

project_custom_attributes and group_custom_attributes used datetime
instead of datetime_with_timezone column type in database schema. But
actually migration defines `t.timestamps_with_timezone`.

If user has configure the setting then it will be passed to gitlab-shell
and gitlab-workhorse